This invention relates in general to a device which includes a machine part which is mounted on a support for movement in at least one direction and produces a regularly recurring inertia force and an actuator which is mounted on a support and has one moving actuator part connected to the machine part and is displaceable in the direction of the inertia force.
In machines of this kind, particularly injection-molding machines for plastics, but also in high-speed presses or the like, relatively strong oscillatory insertia forces are produced by the intial acceleration and braking retardation of the moving parts, such as molding plates, pistons, lever gear, etc., which forces are transferred to the support and cause a correspondingly strong vibration or jolting of the entire machine. Depending on the characteristics of the moving mechanism or on the adjusted speeds, the acceleration and retardation forces may compensate each other or have a positive or negative resultant in the direction of motion. In the last mentioned case, the entire machine starts to creep on the floor in the direction of the resultant of the inertia force. If the machine is firmly screwed to the floor, the acting forces may cause cracks in the support or in the bed, and noise is conducted through the bed into the building.
To eliminate such undesirable phenomena, it is known to accelerate additional masses in the direction opposite to the motion of parts producing inertia forces. This may partly or completely compensate for the inertia forces. A common drawback of such arrangements, however, is that they are relatively complicated, expensive and bulky. In addition, they increase not only the total weight of the machine but also the power requirements. In many instances, this additional equipment also makes the access to the machine parts more difficult.